Delayed-action tripping device



Sept. 26, 1967 c. METTLER DELAYED-ACTION TRIPPING DEVICE 3 Sheets-Sheet1 Filed July 21, 1965 INVENTOR. 6244 40 M57745? BY :JM

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Sept. 26, 1967 c. METTLER DELAYED-ACTION TRIPPING DEVICE 3 Sheets-Sheet2 Filed July 21, 1965 INVENTOR. 6421 a M7n 5Q C. METTLER DELAYED-ACTION.TRIPPING DEVICE 4 Sept. 26, 1967 3 Sheets-Sheet 5 Filed July 21, 1965Arr/I544!!! INVENTOR.

64M 0 i/irrziie United States Patent O 3,344,244 DELAYED-ACTIGN TRIPPINGDEVICE Carlo Mettler, Zurich, Switzerland, assiguor t Redon Trust,Chiasso, Switzerland Filed July 21, 1965, Ser. No. 473,612 3 Claims.(Cl. 20tl34) The present invention relates to improvements in delayed-action tripping devices and more particularly topneumatic-actuated tripping devices suitable for firing explosivecharges.

There are already known tripping devices fpr said purpose, but they areformed by a large number of small pieces, usually to be assembled incomplicated way, what makes them diflicult and expensive to manufactureand their operation not as safe as desirable.

The present invention consists in a pneumatic delayedaction trippingdevice comprising a very limited number of sturdy, easily assembledpieces so as to result in an easy fabrication and a dependableoperation.

Naturally the present invention can also be used for many applicationsother then the one said above, for instance for delayed-action switch orcommutator controls and the like.

More precisely an improved tripping device according to the presentinvention comprises:

A casing or body member and a pressure plate extending over one side ofsaid body member; a rigid diaphragm that separates in a hermetical waythe space enclosed between said body member and pressure plate, in twochambers, in said diaphragm there being foreseen a guiding opening for acylindrical hollow body, slidable therein, against the action of aspring, every time a pressure is applied to the pressure plate; aplunger means, slidable within said hollow body and adapted to actuate,directly or indirectly, the firing pin; a locking means for said firingpin, combined with a pneumatically operating means, and adapted torelease the firing pin only when, upon an external pressure persistingon the pressure plate, in the two non-hermetic chambers there isestablished again the pressure balance that had been upset at the timeof the displacement of said pressure plate.

The accompanying drawings illustrate schematically, in the way ofexamples, two forms of embodiment of the improved tripping deviceaccording to the present invention.

More precisely, in the drawings:

FIGURES 1 and 2 show respectively a plan view and a diametral section ofa first form of embodiment of the tripping device according to thepresent invention, wherein the diiferent members are shown in their restposition.

FIGURE 3 shows in diametral section, the same device of FIGURES 1 and 2,however with the different members in the position in which they come tobe as soon as the pressure plate has been lowered because of an externalaction.

FIGURES 4 and 5 show respectively, in a plan view and a diametralsection, the same device as in the preceding figures, but wherein thedifferent members are in the position they take up after the tripping.

FIGURES 6, 7 and 8 show, in a diametral section, another embodiment ofthe tripping device according to the present invention, and wherein thedifferent members are respectively represented in the rest position, inthe position they take up as soon as the pressure plate has beenlowered, and finally in the position they take up after the tripping.

As it is apparent from the drawings, the form of embodiment illustratedin the FIGURES from 1 to 5 comprises: a body or casing 1, made of rigidmaterial, closed on top by a cover or pressure plate 2, connected to theupper edge of the casing 1 by means of a flexible and gas-tight element2'. The inside of the space enclosed between the casing 1 and the cover2 is divided in two chambers by a rigid diaphragm 3, having in itscenter a hole adapted to constitute a seat, with a certain play, for thesliding hollow stem or cylinder 2a, fast with the pressure plate 2.Inside the cavity of said stem 2a there are received a helical spring 4,and a small plunger 5, the cylindrical wall of the stem 2a having at agiven point an opening 2d, the purpose of which shall be explainedlater.

Beneath the plunger 5, that terminates at its bottom with a conical tip,there is arranged the tripping member 6, carrying the firing pin, andcombined with the locking lever 7, pivoted in O, and an arm whereof isprovided with a tooth 7b which, through an aperture foreseen in the stem2a, is in contact with the wall of the stem itself. The other arm ofsaid lever carries at its end a tooth 70 which, in the rest position,keeps the tripping member 6 in a cocked position, that is the firing pina distance away from the percussion cap 9, arranged in the wall of thecasing or body 1.

With the lever 7 there is combined a bladder or lung 8, of a flexibleand elastic material, filled with air, and communicating with the upperchamber of the device in question.

Before its operation, the different members of the tripping device beingthe object of the present invention are in the position clearlyillustrated in the FIGURES 1 and 2, and under these conditions saidtripping device or igniter may be placed in the ground with cover 2,near the surface, now in a raised position, as it can be seen in FIGURE2. In this position, which is the normal one, the spring 4 does notcarry any load and the bladder 8 has its natural shape. As alreadystated the locking lever 7 cannot rotate about its pivot 0 because itstooth 7b is in contact with the stem 2a of the pressure plate 2, andconsequently the tooth 7c of said lever keeps the tripping member 6 inits cocked position as shown in FIG. 2.

At the instant when (see FIG. 3) on the cover or pressure plate 2 of thedevice comes to bear a load or a pressure P equal or higher than thepredetermined actuating load, the cover 2 is brought down until it bearson the diaphragm 3. In such a position, the spring 4 is pressed down andbears on the small plunger 5 which, in turn, acting on the inclinedplane of the tripping member 6, tends to push this last one towards thepercussion cap 9. The locking lever 7, pushed in turn by the trippingmember 6, tends to rotate since its tooth 7b succeeds in penetratinginto the opening 2d existing on the stem 2a of the pressure plate 2, butto lock it, intervenes the bladder 8 which, because of the suddenlowering of the pressure plate 2, and the consequent volume reduction ofthe air enclosed between it and the diaphragm, becomes inflated,opposing the displacement of the lever 7.

If the load or pressure P, bearing on the pressure plate 2, isinstantaneous, that is due to a shock, a pressure Wave caused by nearexplosions or the like, once the stress is over, the spring retrievesupwardly the pressure plate 2 and all the components of the firingdevice return in the exact initial or rest position, as shown in theFIGURES 1 and 2.

If instead the load P persists on the pressure plate 2 (FIGURES 4 and 5)then, a few instants after the application of said load, the compressedair contained above the diaphragm 3 leaks through the clearance existingbetween the guiding cavity, fast to the diaphragm 3 and the stem 2a ofthe pressure plate, as long as there is reached a perfect balancebetween the pressure of the air contained above and that contained belowthe diaphragm 3. Once said balance is reached, the bladder 8 presents noresistance anymore to its crushing and accordingly the locking lever 7rotates about its pivot 0, thus disengaging its tooth 70 from thetripping member 6 which, under the thrust of the spring 4, will snapsliding horizontally and bringing the firing pin fast with same againstthe percussion cap 9, thus causing its firing.

The form of embodiment illustrated in the FIGURES 6, 7 and 8 isdifferent from the one described above although having the same basicmembers.

Indeed, the device as illustrated in said figures comprises: a casing orbody 11, a cover or pressure plate 12, connected with the upper edge ofthe casing 11 through an elastic ringshaped means 12a closing ithermetically. The inner space thus resulting is divided in two parts bythe rigid diaphragm 13, which has in its center a guiding hole or sleeve13a, within which extends and slides the hollow cylindrical element 15in the inside whereof are received a helical spring 14, and the trippingmember 16, which in this instance has the shape of a cylinder or smallplunger carrying at'its lower end the firing pin adapted to hit thepercussion cap 19, arranged in the bottom of the casing 11. On a sectionof the extension 13a of the diaphragm 13 there is pivotally connectedthe locking lever 17, through its pivot O. Laterally to same, in thediaphragm 13 there is foreseen a hole 1%, with guiding walls, withinwhich slides the small piston 18. The rod of said piston has a holewherein there is inserted, so as to be able to effect some oscillations,the tail 17a of the lever 17, so that the piston 18 controls themovements of the lever 17, that is allowing same to carry out or not therotation about its pivot O, as it will be better explained later.

The lever 17 further has also a tail 17b which, in the rest position, isin contact with the inner wall of the hollow plunger 15, and oppositeits tail 17a a tooth 170, which is the element of said lever locking thetripping member 16 in a position away from the percussion cap 19, untilthe time when the blasting has to occur.

The operation of the above described device is practically the same asthat of the preceding device. Indeed, when said device is in its restposition, the pressure plate 12 is in a raised position, the spring 14is not pressed, and the piston 18 is in its lowered position. As alreadymentioned, in this position of the mechanism, the lever 17 is preventedfrom rotating about its pivot since its tooth 17b is in contact with theouter wall of the hollow element 15, and therefore the tooth 17c keepsthe tripping member 16 cocked and thus away from the cap 19.

At the instant when (FIG. 7) on the pressure plate 12 comes to bear aload P equal or higher than the calibratron load, said pressure platedrops down until it rests on the diaphragm 13, thus compressing thespring 14 and this, hearing on the tripping member 16, tends to rotatethe locking lever 17. But, at this first instant said lever is preventedfrom rotating because the air contained above the diaphragm 13 has beencompressed and bears with a pressure higher than that in the restcondition on top of the piston 18, thus preventing any movement of thelocking lever 17, to which it is connected.

If the load P bearing on the device is an instantaneous one, once thestress is over, all parts return in the rest position as shown in FIG.6.

If instead the load or pressure P persists (FIG. 8), then after a fewinstants there is established again a balance between the pressures inthe two chambers, above and below the diaphragm 13, whereby, persistingon the tripping member 16 the pressure exercised by the compressedspring 14, and no overpressure being applied anymore on top of thepiston 18, this can move upwardly, allowing the lever 17 to rotate aboutits pivot O, whereupon the tooth 17b will enter into the opening aforeseen on the body '15 wall, and the tooth 17c will become disengagedfrom the tripping member 16 which, under the action of the spring 14,will hit the percussion cap 19.

From the above description it is apparent how the delayed-actiontripping devices, object of the present invention, ofier remarkableadvantages as compared to similar already known devices. Indeed they areconstituted by few very sturdy elements, easy and cheap to manufacture,and of safe operation, just because of this simplicity of theirs and forthe fact of not including elements capable of deteriorating with thetime.

Of course, the two devices as illustrated and described above havemerely an illustrative character and by no means a limiting one, andtherefore the different elements constituting them, the materials usedfor their manufacture, and all the constructive details may varyaccording needs without therefore departing from the field of thepresent invention.

What I claim is:

1. A delayed-action tripping device, inoperative by sudden instantaneousstresses, which comprises, in combination a rigid casing enclosure and apressure plate, with a flexible portion of said plate hermeticallysealing said enclosure, a rigid diaphragm provided with a hole, saiddiaphragm dividing said enclosure into two non-airtight chambers; aslidable element, sliding into a hole in said diaphragm and actuated bythe pressure plate against the bias of a spring; a tripping member; alocking means for locking said tripping member in its non-trippingposition; and a delayed time means, said time means and said diaphragmbeing subjected to the prevailing pressure in either of the two chambersresulting from the pressure applied to the pressure plate, said delaymeans acting on said locking means allowing the locking means to bereleased from the tripping member only when persisting pressure isapplied to the pressure plate.

2. A tripping device as claimed in claim 1, and comprising: a pressureplate provided with a hollow stem, extending through and capable ofsliding in a corresponding hole of the diaphragm; a spring and a guidingplunger with a conical tip, received and slidable in the cavity of saidstem; a tripping member, provided with an inclined plane on which restsand bears the conical tip of said plunger; a locking means formed by atwo arm lever, one of the arms whereof being provided with a tailbearing in normal position-on the outer surface of said stem and adaptedto penetrate in an opening provided on said stem itself, at the instantof its tripping, while the other arm is provided with a latching tooth,engaged with the tripping member and urged in its locking position, byan elastic bladder, the inside whereof is communicating with the chamberabove the diaphragm, so that said bladder is filled with air underpressure at the first instant, after the lowering of the pressure plate,while, should the load on said plate persist, the balancing of thepressures in the two chambers separated one from the other in a nonairtight way by the diaphragm, occurs, the pressure inside the bladderdecreases and it does not oppose anymore the movement of the levercausing the release of the tripping member.

3. A tripping device as claimed in claim 1, in which the pressure platerests on a cylindrical hollow element, closed at its top, and receivingin its cavity the tripping member, and a spring, bearing on said member,with this member there being combined a locking lever, pivoted in anintermediate point thereof and provided, at one of its ends, with atooth adapted to normally keep in a cocked position the tripping member,and at its other end a first tail portion, in contact with saidcylindrical element when the lever is in its rest position, and a secondtail portion engaged with the delayed time element, constituted by apiston slidable in an opposite seat provided in the diaphragm, andsubjected to the pressure prevailing in the chamber closed by thepressure plate.

(References on following page) 5 5 References Cited FOREIGN PATENTSUNITED STATES PATENTS 948,276 1/1964 Great Britain. 2,465,009 10/1945Chase 102-16 I 2,857,842 10/1958 Mahn 102 8 BERNARD A. GILHEANY, PnmaryElamzner.

3,098,439 7/1963 Berger 102-8 5 H. E. SPRINGBORN, Assistant Examiner.

1. A DELAYED-ACTION TRIPPING DEVICE, INOPERATIVE BY SUDDEN INSTANTANEOUSSTRESSES, WHICH COMPRISES, IN COMBINATION A RIGID CASING ENCLOSURE AND APRESSURE PLATE, WITH A FLEXIBLE PORTION OF SAID PLATE HERMETICALLYSEALING SAID ENCLOSURE, A RIGID DIAPHRAGM PROVIDED WITH A HOLE, SAIDDIAPHRAGM DIVIDING SAID ENCLOSURE INTO TWO NON-AIRSIGHT CHAMBERS; ASLIDABLE ELEMENT, SLIDING INTO A HOLE IN SAID DIAPHRAGM AND ACTUATED BYTHE PRESSURE PLATE AGAINST THE BIAS OF A SPRING; A TRIPPING MEMBER; ALOCKING MEANS FOR LOCKING SAID TRIPPING MEMBER IN ITS NON-TRIPPINGPOSITION; AND A DELAYED TIME MEANS, SAID TIME MEANS AND SAID DIAPHRAGMBEING SUBJECTED TO THE PREVAILING PRESSURE IN EITHER OF THE TWO CHAMBERSRESULTING FROM THE PRESSURE APPLIED TO THE PLATE, SAID DELAY MEANSACTING ON SAID LOCKING MEANS ALLOWING THE LOCKING MEANS TO BE RELEASEDFROM THE TRIPPING MEMBER ONLY WHEN PERSISTING PRESSURE IS APPLIED TO THEPRESSURE PLATE.